Linked List in Python

In this blog, I’ll help you create Linked List using OOPs in python.

#!/usr/bin/env python3
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
class LinkedList:
    def __init__(self):
        self.head = None

The above code you see is all you need to create a Linked List Data Structure. Everything else that we write is the operations on Linked List.

Some of the operations on Linked List that I’ll implement in the next code template includes,
1. Insert the First Element i.e. the head or root element.
2. Append nodes to list from the end.
3. Append at the start of the list.
4. Insert node at any position in the list.
5. Remove the node at any given index.
6. Remove the last node in the list.
7. Remove the first node in the list.
8. Get node at any given index in the list.
9. Size of List.
10. Remove all elements from the list.

#!/usr/bin/env python3
class Node:
    def __init__(self, data):
        self.data = data
        self.next = None
class LinkedList:
    def __init__(self):
        self.head = None
        self.last = None
def insertFirst(self, data):
        self.head = Node(data)
        self.last = self.head
def size(self):
        count = 0
        node = self.head
        while node:
            count += 1
            node = node.next
        return count
def getFirst(self):
        return self.head
def getLast(self):
        return self.last
def clear(self):
        self.head = None
def insertLast(self, data):
        if self.last:
            self.last.next = Node(data)
            self.last = self.last.next
        else:
            self.head = Node(data)
            self.last = self.head
def getAtIndex(self, index):
        node = self.head
        count = 0
        while count != (index):
            node = node.next
            count += 1
        return node
def insertAt(self, data, index):
        if index == 0:
            node = Node(data)
            if self.head:
                temp = self.head
                node.next = temp
                self.head = node
            else:
                self.head = node
                self.last = self.head
elif index >= self.size():
            self.insertLast(data)
        else:
            new_node = Node(data)
            beforeIndex = self.getAtIndex(index - 1)
            atIndex = beforeIndex.next
            beforeIndex.next = new_node
            new_node.next = atIndex
def printList(self):
        node = self.head
        while node:
            print(node.data)
            node = node.next
def removeFirst(self):
        if not self.head:
            raise IndexError
        else:
            removedValue = self.head.data
            self.head = self.head.next
        return removedValue
def removeLast(self):
        if not self.head:
            raise IndexError
            return
        if not self.head.next:
            self.head = None
            return
        prev_node = self.head
        curr_node = self.head.next
        while curr_node.next:
            prev_node = curr_node
            curr_node = curr_node.next
        valDeleted = curr_node.data
        self.last = prev_node
        prev_node.next = None
        return valDeleted
def removeAtIndex(self, index):
        if index == 0:
            self.removeFirst()
        elif index == (self.size() - 1):
            self.removeLast()
        else:
            prev_node = self.getAtIndex(index - 1)
            next_node = prev_node.next.next
            prev_node.next = next_node
# --------------------  TEST THE LINKED LIST DS --------------------
list = LinkedList()
list.insertFirst(5)
list.insertLast(7)
list.insertLast(9)
list.insertLast(11)
list.insertLast(13)
list.insertAt(25, 0)
list.insertAt(35, 6)
list.insertAt(45, 3)
print("Size of List is {}".format(list.size()))
print("First element of list is {}".format(list.getFirst().data))
print("Last element of list is {}".format(list.getLast().data))
print("--------------------LIST ELEMETS--------------------")
list.printList()
print("Get element at index 3", list.getAtIndex(3).data)
print("Removing first element from list", list.removeFirst())
print("Remove last element from list", list.removeLast())
print("Last Element is", list.getLast().data)
print("Remove last element from list", list.removeLast())
print("Last Element is", list.getLast().data)